In this study, waste cooking oil ethyl ester (biodiesel) was produced via basic transesterification reaction, ethyl ester-diesel-methanol ternary blends including different volume ratios of alcohol (2 and 4) were prepared, densities of the ternary blends were measured at different temperatures (278.15, 283.15, 288.15, 293.15, 298.15, 303.15, 308.15, 313.15, 318.15, 323.15, 328.15 and 333.15 K) according to ISO 4787 standard, and the exponential model as a function of temperature was derived using the least squares method to predict density values. Moreover, the exponential model was compared to the well-known linear model, and the reliability of these models was investigated using the density data of rapeseed oil methyl ester-diesel-bioethanol ternary blends measured by Barabás. According to result, the exponential model, suggested by the authors, qualitatively and quantitatively better reflect the variations in densities of different biodiesel-diesel-alcohol ternary blends measured by the authors and Barabás.